It called the motion brought by another opposition party, the Economic Freedom Fighters (EFF), to be brought forward from 22 February so parliament can "remove Jacob Zuma".

Analysis: Going, going.... gone?

By Lebo Diskeo, BBC News, Johannesburg

Although it was hardly an unexpected announcement, there was still a sense of disbelief among the waiting journalists as Mr Magashule announced the NEC has asked Mr Zuma to step down.

After such a long wait, we had half expected the ANC to say they had given him more time, or reached some sort of compromise.

But surprise gave way to bemusement as Mr Magashule side-stepped repeated requests for clarification on what the ANC will do if President Zuma refuses to resign by Wednesday.

As for whether the ANC would support an opposition motion of no confidence, Mr Magashule said he did not know.

But when asked what Mr Zuma said when he was told of the NEC's decision, Mr Magashule choice of words were pointed: the president had said he was "a disciplined member of the ANC".

It was a term repeated several times during the briefing.

In other words, as far as the ANC is concerned - it is done.

What has Mr Zuma done wrong?

Mr Zuma's presidency has been overshadowed by allegations of corruption which he has always vehemently denied.

In 2016, South Africa's highest court ruled that Mr Zuma had violated the constitution when he failed to repay government money spent on his private home.

Last year the Supreme Court of Appeal ruled that he must face 18 counts of corruption, fraud, racketeering and money-laundering relating to a 1999 arms deal.

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Media captionThe Zuma presidency: Scandals and successes

More recently, Mr Zuma's links to the wealthy India-born Gupta family, who are alleged to have influenced the government, have caused his popularity to plummet.

Both Mr Zuma and the Guptas deny the allegations.

Is Mr Zuma legally obliged to quit?

The formal request to resign is difficult to resist, but he is not legally obliged to do so and could technically carry on as president despite losing the support of his party.

However, should he continue to defy his party, he would be expected to face a confidence vote in parliament. Mr Zuma has survived other such votes but he is not expected to pull it off again. A confidence vote would be considered a humiliating process for him and the party.

In terms of the constitution, it will require the entire cabinet to resign and for the parliamentary speaker to serve as acting president until MPs elect a new president.

Image copyrightGetty ImagesImage caption
Many in the ANC hope that removing Mr Zuma will boost the party's chances in the 2019 elections

Why is this happening now?

It wants to project a fresh image for next year's general election. Having served two terms in office (South African presidents are elected by parliament), Mr Zuma cannot legally return to power in any case.

On Monday, opposition parties called for an early election.

"Anyone from the ANC that wants to lead this country, must get their mandate from the people of South Africa," DA leader Mmusi Maimane told reporters.